This invention relates generally to a coupling means for use in maintaining driving force to machinery during routine operations, and more specifically pertaining to an improved torque limiting overload coupling device that effects drive disconnection and curtails machinery rotation with reduced incidence of damage to the operating components of said coupler, and the machinery at large.
There are a significant number of a variety and styles of associated shaft, flange, and dial type of coupling devices that are available in the prior art, and usually these devices are provided for interconnecting between the drive shaft of a motor, its speed reducer, or the like, and the main driven shaft for supporting components of the machinery apparatus being revolved. Many of these coupling devices are constructed in the category of flexible type couplings, and any of a variety of said connectors are designed for providing a transmission of the driving or rotational force or torque from a drive shaft to the intended driven shaft, but yet being capable of disconnection in the event that a binding force creates an excessive torque that prevents or significantly reduces turning of the component upon which work is being performed. In addition, safety means have on occasion been designed into these type of couplings, functioning in the manner as safety devices to prevent the exertion of excessive torque forces upon the driven means or shaft from damaging the drive means or shaft and its prime mover, or even from causing damage to the tool functionally performing some work upon a work component mounted upon the machinery, or from exerting excessive torque thereon in the first instance. Many of these safety devices have been designed in the category of machanically activated torque couplers, and as can be seen in the U.S. Pat. to Schultz, No. 2,771,171, a variety of magnetic pole pieces are arranged within a rotor means and normally effect a revolving of a driven member and its axial shaft for furnishing force transmission for rotation of a pair of axial shafts, but yet in the event that excessive force is applied to one of the shafts then the magnetic means is disengaged for curtailing the rotation of the driven shaft. The shown mechanically operated torque coupler of this U.S. patent, while it may be effective in its operations, is quite dissimilar from the mechanically actuated torque limiting means of the current invention.
An additional variety of magnetic coupling devices for preventing overload force from being exerted upon a driven shaft, and which finds significant usage in industry, are shown in the U.S. Pat. to Cowell, No. 3,221,389, and the U.S. Pat. to Gollos, No. 3,339,819. This latter patent is pertinent for disclosing a series of spherical projections that contact and intermesh with cups formed upon an opposite angular surface with these two separate components being held together through the agency of permanent magnets.
Further types of magnetic torque limiting devices, and specifically for use in low force operating mechanisms, such as phonograph record players or sound recorders, are shown in the two U.S. Pat. to Tiffany, No. 1,136,739, and Cornwall, No. 2,300,778.
The combination of magnetic couplers having spring biasing to determine the degree of force necessary for disengaging a coupling has also been available in the prior art, as shown in the U.S. Pat. to Allen, No. 3,053,365. And, other forms of connectors, which generally have utilized the permanent magnet approzch for effecting torque control are shown in the additional U.S. Pat. to Woolley, No. 3,277,669; the U.S. Pat. to Hornschuch, et al., No. 3,159,725; the U.S. Pat. to Spodig, No. 2,943,216; the U.S. Pat. to Beeston, Jr., No. 2,885,873; and finally, the U.S. Pat. to Hoad, No. 2,746,691, and which utilizes a frictional connection between magnets for determining the degree of torque necessary to effect discoupling of its torque limiting device.
Various ball detent couplings are available in the art, and some are shown in the U.S. Pat. Nos. 3,701,404; 3,680,673; 3,893,553; 3,981,382; 3,979,925; 3,942,238; 3,927,537; 3,930,382; and 3,866,728.
In addition, various machanical coupling devices, also utilizing the ball bearing type means for holding a driving part to a driven part are shown in the prior art, and such can be seen in the U.S. Pat. to Steinhagen, No. 3,774,738. It is significant to note, though, that in this prior art patent, to effect the decoupling of the device when an overload torque condition is encountered, that both the coupling balls must ride upwardly from their pockets formed within the driven member, and simultaneously, the same balls must move downwardly with respect to the pockets formed in their rotatable or driven means. Thus, there must be a plural axial movement of the coupling balls with respect to both the driven and rotatable parts of the shown coupling, and when such a condition prevails within this style of a coupling, usually back lash occurs, rotational looseness is encountered, and furthermore, since the coupling balls must ride free from their seating within diametrically spaced pockets, there is a tendency for said balls to become damaged after not too prolonged a period of time of usage. Similar type connections or machine element couplings are shown in the U.S. Pat. to Vassakos, No. 1,883,164, and the additional patent to Steinhagen, No. 3,722,644.
Other types of power transmitting mechanisms, having flexible couplings therein, are shown in the U.S. Pat. to Ely No. 1,541,489, in addition to those couplings also shown in the U.S. Pat. Nos. 4,006,608; 2,818,712; 3,050,965; 3,942,337; 1,566,553; 3,148,499; and the torque limiting brake shown in the U.S. Pat. No. 4,046,237.
The invention described in the Torque Limiting Overload Coupling application set forth in the cross reference to related application has been significantly improved through the innovations of this current invention in three major aspects; one being the ability of the structure of this invention to suspend the detent balls from the driving means and locate their seating within detent seats within the driven means through contact of these components solely within one axial half or hemisphere of the spherical detent balls, or all along one axial side thereof, to provide a connection between such components in a mechanism coupler that can provide precision control of the coupler during usage, effect a decoupling when that predetermined torque is encountered, and do so solely through the use of the suspended, as distinct from sandwiched, balls without need of any further tapering pins or the like, as described in said prior application, while thirdly, and to reduce the incidence of damage to such detent balls, by having the balls, upon their other surface, rest against a bearing mounted race that can likewise enter into some degree of revolving with the detent balls as and after they become unseated from within their driven member. These improvements have greatly enhanced the performance characteristics of this type of a coupling particularly when used in precision intermittent motion applications, so as to produce a minimum of backlash, add to the precision of work component positioning by means of any associated dial index, and to perform consistently in tripping when that excessively predetermined torque has finally been reached.
It is, therefore, the principal object of this invention to provide an overload torque coupling means wherein the ball detents are both positioned and held between the driving and driven means by surface contact as substantially only made upon one axial side of each said ball detent means.
Another object of this invention is to provide detent seats formed in a driven means and which are precisely contoured at their surface edges so as to authorize the ball detent to shift there out when a predetermined force is encountered, while reducing the incidence of abrasive damage to the ball or their seat surfaces when decoupling occurs.
Another object of this invention is to provide an improved style of overload torque decoupling means which functions with a minimum of rotational backlash, thereby eliminates all rotational looseness, as to improve the precisional operation of the driven member particularly when it may comprise or be connected with an indexing table, or the like, while at the same time achieving a more precise and consistent decoupling of the assembly when a trip torque is encountered.
Still another object of this invention is to furnish an overload torque coupler designed to enhance and lengthen the operational life of such a device by incorporating free moving bearings intermediate its ball detent and the pressure exerted by the resilient or spring means thereon in gauging the fixed torque setting for the assembly.
Yet another object of this invention is to provide an overload torque decoupling assembly incorporating a plurality of ball detents, wherein the detents are staggered so that once a discoupling occurs, the driving member will ride free with respect to the motion impeded driven member.
Still another object of this invention is to provide a means for accomplishing machinery deenergizing or shut-down momentarily after its decoupling means has attained disconnection.
Yet another object of this invention is to provide an overload coupling that may be conveniently inserted within the drive means to machinery, and having sufficient flexibility in its mounting so as to provide for its interconnection between a shaft-to-shaft, shaft-to-flange, flange-to-flange, or shaft or flange-to-dial type of assembly.
These and other objects will become more apparent to those skilled in the art upon reviewing the summary of this invention, and upon undertaking a study of the description of its preferred embodiment, in view of the drawings.